Normal Kubota Rear Float-Detent Valve Operation?

[MtnViewRanch]

So if there is air getting into the system, would it effect the rear remotes more than the other hydraulic functions? (3pt, loader lift, loader curl, 3rd function)

With the rear remote in neutral, Should I expect more and more air to get pushed into the cylinder and cause it to collapse more and more as time went on?

I'm still not sure how to check if the hydraulic fluid is getting foamy without a dipstick. The MX only has a sight glass. Should I be able to look down the fill hole in the back and see the fluid?

You should be able to see through the sight glass. It will not be solid in color, or solid clear. It would be milky looking.

As far as where and how the system is getting air in it and it does not seem to affect other cylinders I can't say.

All I know is that you are getting air into the top link cylinder and that is why you have the spongy acting top link. You have air in the unit, there is zero doubt in my mind about that. Fluid does not and will not act as a spring.

 

[BCrouse]

I did the same test with the implement off the ground with the hydraulic toplink fully collapsed, only this time i left the remotes plugged in. Since I had less than 1/4" of movement with the cylinder disconnected, I wanted to know how much it moved with it connected. I waited the same time to go and check it, 2.5hrs. I'm not sure how long it took but the cylinder was extended all the way to let the implement rest on the ground. This was on the float-detent valve. I did not test the standard valve yet, but i assume it will be the same.

Is this expected behavior? Does this tell me some additional information?

 

[BCrouse]

Cylinder disconnected from rear remotes. Its got a 1200lbs boxblade on it




Same test. Same boxblade. but I left the cylinder attached to the float-detent rear remote valve.






Timeframe on both was 2.5hrs. I am unsure if the "cylinder connected" test hit the ground before the 2.5hrs, but the implement was resting on the ground when I went out to check on it again at 2.5hrs.

 

[MtnViewRanch]

This confirms that there is a definite problem with your control valve-s.

 

[BCrouse]

Here is the (1) position standard valve. Same test, same boxblade. 2.5hrs on the clock.

Start


2.5hrs later. aprox 3" of the cylinder showing





I have not done the center (2nd posistion) Float-Detent Valve. If the result is in between this result and the 3rd posistion float-detent valve, would you say that the issue is with the 3rd posistion valve in some manner?

 

[Leejohn]

Mine does it also, but I don't think you well stop that. The rear remote valves on Kubota's are not near as good as the loader valve.

 

[BCrouse]

Mine does it also, but I don't think you well stop that. The rear remote valves on Kubota's are not near as good as the loader valve.

Do you have both types of valves? Standard (SCV) and Float-Detent? And they both act the same as what mine do?

 

[Leejohn]

I just have one standard rear remote spring center.

 

[ovrszd]

All three of mine do that when powering my top link.

Brian suggested restrictor washers. Tried that. Slight improvement. Slowed movement to much to suit me.

Here's the best description of what's going on that I've heard. Got this from a trusted local hydraulic guru.

The tank return dumps above the fluid level in the tank. When the cylinder is extended it creates a vacuumn in the tank return line and sucks air into the valve.

Maybe. Maybe not. I don't believe there's anything mechanically wrong with my valves or cylinder.

 

[AllByteNoBark]

Could a check valve be used to prevent that? Far from a hydraulics expert, but sounds like issues I've faced elsewhere that a check valve helped resolve.